I have no idea. Nobody does...there's not a concrete consensus as to when "human life" as we know it begins. Bottom line, personal beliefs aside, that's how it is. That's why, even though I'm someone that personally can't stand the idea of my wife or girlfriend getting an abortion, I have to go with the pro-choice option. People with opinions and beliefs that dictate they don't want one won't get one and those without them will choose to get one if they must. I can live with that. It's a compromise.
If you read any of my other posts you would have seen that I specifically said that abortions after the 3rd month shouldn't be alowed except in serious legal cases (rape, incest, etc.) or medical complications.
I don't know what it is. I don't think anyone actually does. Personally, I think after 3 months it's close enough to being "human" that abortions shouldn't be allowed them except in extreme cases. But again, that's me. My belief isn't "prove-able" enough at this point where I'd feel comfortable with sweeping federal laws declaring abortion illegal. I have further issues with that sentiment since so much of the opinion behind it is faith-based, particuarly faith that often thinks other forms of birth control (condoms, birth control pills, morning after-pills, sex education, etc.) are wrong as well. I fear that sweeping bans of abortion at this point, when it really is still a very fuzzy issue whether people want to admit it or not, will spill over into these other issues, or influence additional debates, like the issue of stem cell research.
I personally think after 3 months it is a child and such laws could be applicable except in special cases. I do not, however, know that I am right. Until it can be definitively clarified, I am far more comfortable with the idea of people being able to choose what they wish. I find the continued sentiments that dismiss women who get abortions as murderers or selfish or that they "just want to keep their figure" or they don't care to be MASSIVELY insulting. It's not an easy procedure people just leap into. I've had friends and family who have chosen to have one and it was NOT an easy choice for them. I'm baffled that people who oppose it can so easily write off seemingly everyone who gets one as being some kind of unfeeling monster. It's not that simple...like the entire debate, it's not a cut and dry, black and white issue.